Dark halo or bigravity?

Issue		Eur. Phys. J. Special Topics Volume 163, October I 2008 Atomic Clocks and Fundamental Constants


Page(s)		291 - 296
DOI		10.1140/epjst/e2008-00825-5
Published online		25 October 2008

Eur. Phys. J. Special Topics 163, 291-296 (2008)
DOI: 10.1140/epjst/e2008-00825-5

N. Rossi

Dipartimento di Fisica, Universtità degli Studi dell'Aquila, 67010 Coppito (AQ), Italy and INFN, Laboratori Nazionali del Gran Sasso, 67010 Assergi (AQ), Italy

nicola.rossi@aquila.infn.it

Abstract
Observations show that about the $20\%$ of the Universe is composed by invisible (dark) matter (DM), for which many candidates have been proposed. In particular, the anomalous behavior of rotational curves of galaxies (i.e. the flattening at large distance instead of the Keplerian fall) requires that this matter is distributed in an extended halo around the galaxy. In order to reproduce this matter density profiles in Newtonian gravity and in cold dark matter (CDM) paradigm (in which the DM particles are collisionless), many ad-hoc approximations are required. The flattening of rotational curves can be explained by a suitable modification of gravitational force in bigravity theories, together with mirror matter model that predicts the existence of a dark sector in which DM has the same physical properties of visible matter. As an additional result, the Newton constant is different at distances much less and much greater than 20 kpc.

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